We use the discos up at the farm to their fullest capabilities almost every weekend. Apart from being a but on the agricultural side, they are truly amazing cars.
After having a proper look, It would appear that it does not have the factory fitted CDL, no shaft on top of the transfer case. Thanks @Volvirgin for the info :D
Our other D2 which is 6 months older does, so I may fit a transfer case at a later date. I will say that the factory traction control does indeed work, but is far more aggressive than the seamless power delivery of having a true locking centre diff.
Slight vibration at 95-105 that I can power through, rear rotoflex/guibo/propshaft rubber is pretty dry and nasty, Ill see if that fixes it up.